Beading process



Feb. 17, 1942.

- T. 'R. DUNN BEADING PROCESS Filed Aug. 25,1939

INVENTOR 7.' 1?. IV/Y/V AnMWw ATTORNEY Patented Feb. 17, 1942 BEADING PROCESS Thomas R. Dunn, Bloomfield, N. .L, assignor to Westinghouse Electric & Manufacturing Company, East Pittsbur Pennsylvania Pa.,- a corporation of Application August 25, 1939, Serial No. 291,855

3 Claims.

My invention relates, to quartz lamps and especially to the sealing of the conductors to a quartz container. I

An object of the invention is to prevent the cracking of the glass around the conductors during their sealing in thequartz container.

Other objects and advantages of the invention will become apparent from the following description and drawing, in which:

Figure 1 is an elevational view of a quartz dis-. charge device in which the invention is incorporated.

Figures 2 and 3 are elevational views disclosing two steps in the formation of glass about one of the single conductors.

Figure 4 is an elevational view disclosing the usual form of glass beads about a double conductor.

Figures'5 and 6 are elevational views of two steps in the formation of the unified bead about a double conductor, according to the invention.

Figures-7 and 8, are views, partly in elevation and partly in cross-section, illustrating first the double conductor bead, and then the single conductor bead, being sealed in the quartz discharge device of Figure 1. I

The invention is an improvement over the invention described in the oopending application of George A. Freeman, Serial No. 284,575, filed July 15, 1939, for Seal for quartz lamp In Figure 1 is disclosed a quartz discharge device having a quartz tubular container lil'with ends I l and I2, generallyof a graded quartz glass,

, ably a strip of thorium surrounded by a coil of tungsten to correspond with the other electrode M. The other electrode l6, preferably has merely an extension l8, to form a starting electrode or starting tip to break down the gaseous atmosphere between I1 and I8, and then to ignite the It has been found, that there were seal cracks originating around the external ends of lead-in conductors due to weakness at those points. It

is the object of the invention to provide amethod for overcoming the cracking of the glass around the conductors.

In Figure 2, I have disclosed the conductor l3, about which is formed the usual bead of glass Hi. The inner end I4 has not yet had attached thereto, the thorium, and its coil of tungsten wire. 0n the outer end of the glass bead, I form an additional amount of glass material, such as indi- I5and [6, with the usual bead 20 of the prior; art. I have discovered that with the particular glass utilized for sealing to quartz containers,

that the bead about the double conductors takes the barrel shape illustrated in Figure 4, with a thickened middle portion and very much thinner end portions 2| and 22. When the barrel portion is being sealed to the quartz container, the ends 2| and 22 of the bead are mechanically weak, so that when the conductors l5 and [6 are held, the glass will tend tocrack at the weakened end 22. The connection of the container to such a bead is generally thin and mechanically weak.

Accordingly, I take the conductor l5, and place about it a'dumbbell shaped bead with about the usual thickness 23 at the middle portion and additional material 24 and 25 at either end of this dumbbell bead. A similar dumbbell shaped beadare then united into the unified bead disclosed.

in Figure 6. The result is that instead of the barreled shaped device of Figure 4, the unified bead has a thick portion 26 at one end, and a thick portion 21 at the otherend, and a medium sized portion 28 at the center thereof.

Theinner end of I5, namely IT, has attached thereto, a strip of thorium and enclosing coil of tungsten attached thereto, as shown in Figure 1.

During the formation of the double bead, the conductors I5 and [6 were inserted in the special chuck 30, disclosed in. Figure 7, which chuck and method of forming the double bead therein, is

plication of George A. Freeman, Serial No.

' 284,575 previously referred to.

' discharge between the main electrodes I4 and i1. I

, The quartz container ID with its tapered ends 3| and 32 and tubulation 33, is inserted in a chuck 34, and the double beadinserted in the open end 3!, and flame 35 is directed against the more particularly described in the copending aptapered sides 3! to seal it to the center portion 28 of the double bead. The thickened portion 26 adjacent the chuck 30, will prevent any cracking of the head that might otherwise occur if there was a strain thereon due to its being held by the chuck 30. The direction of the flame against the tapered edge 3| of the container melts this edge 3i into a thick mechanically strong seal with the additional material 21 as disclosed in the lower portion of Fig. l.

After the double bead has been sealed in the quartz container, the tube is inverted and the single bead with its thickened end i9 is held adjacent the chuck 36, while the sloping side 32 of the quartz container, is sealed. by means of the flame 35, to the intermediate portion of the single bead.

During the step of sealing the double head, a flow of. nitrogen is passed through the interior of the tube Ill, either through the tubulation or through the open end 32 of the tube, such as is described in the copending application of George a specific embodiment of the invention, it is not desired that the invention be limited thereto, as various other modifications of the same may be made without departing from the spirit and scope of the appended claims.

I claim:

1. The hereindescribed method comprising sealing a bead on a conductor and supplying an additional amount of the bead material next an end for forming an enlargement next the end of the bead, sealing a second bead on a second conductor with alike additional amount of head A. Freeman, Serial No. 242,178, filed Nov. 25,

1938, for Electrode sealing-in.

During the step disclosed in Figure 8, the nitrogen is also'fiowing through the tube as disclosed in the copending application of George A. Free- 3 I man, previously referred to.

Because of the additional strength of the thickened ends of the double bead in Figure 7, and also of the single bead in Figure 8, the cracking of the glass about the electrodes, that was previously experienced, does not happen. The method of supplying the additional glass material at one end'of the single conductor bead, and at both ends of the bead with the double conductors, results in a decrease in the spoilage of thesequartz discharge devices and in mechanicallystrong seals with the tapered sides of the container.

.Although there has been shown and described,

material next an end of said second bead forming an enlargement thereon, and unifying said heads into a single bead about the two conductors and with both of said enlargements unified into and serving to correspondingly enlarge the unified bead thereat.

2. The hereindescribed method comprising sealing a bead on a conductor and supplying an additional amount of the bead materialnext an end for forming an enlargement next the end of the bead, sealing a second bead on a second conductor with' a like additional amount of bead material next an end of said second bead forming an enlargement thereon, and unifying said beads into a single head about the two conductors and with both of said enlargements uni- THOMAS- R. DUNN. 

